The provided texts describe Flutter, an open-source software development kit (SDK) created by Google. Flutter allows developers to build cross-platform applications (for mobile, web, desktop, and embedded systems) from a single codebase using the Dart programming language. The documentation details Flutter's features, including its widget-based UI system, rendering engine, and integration with various Google services like Firebase. Examples of apps built with Flutter and its widespread adoption by businesses are showcased, highlighting its speed, flexibility, and extensive community support.